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Case Study 13: Lead Mining on Islay

Lead Mining on Islay

Mike Cressey

Introduction

Argyll's long history of metalliferous ore extraction is owed to its complicated geology and proximity to the coastline, but the archaeological evidence of what survives of these industries is still poorly understood. No detailed systematic research has been undertaken on these industries with the exception of those remains that survive on Islay (Figure 111) which were the subject of detailed research in the 1990s (Cressey 1993a, 1993b, 1994, 1995).

Whilst Islay was probably the second most important region of lead mining in Scotland after Wanlockhead and Leadhills in Dumfries and Galloway (Barnett 1959, 65), it remains one of the lesser-known production regions in the UK. This case study briefly examines the historic and archaeological record of lead mining on Islay and presents a brief outline of how the research strategy applied on Islay could be broadened to explore the mining evidence of Argyll.

Historical background

Lead ore (Galena) was mined extensively on Islay up until c.1900. The galena formed alongside the basalt dykes that criss-cross the limestone region around Mulreesh in north-east of Islay (Figure 111). The ore formed as a result of metamorphic contact between these two geologies about 600 million years ago (Figure 112). The lead was easily worked where it outcropped near the surface but as these areas became worked out then deeper shaft and adit mining was required. By the late 19th century Mulreesh mine was well established and a lead smelter was built on the east coast close to Port Ascaig.

The travel writer Thomas Pennant (1774) has suggested that lead mining occurred on Islay as early as the Norse Period but there is no archaeological or historical confirmation of this hypothesis. There is, however, archaeological evidence for lead mining from c.1360 (Cressey 1995); in the Middle Ages there was much need of lead for roofing and plumbing of prestigious buildings, like large churches and for alloying with other metals to make pewter vessels.

The earliest historical record of lead mining on Islay is from the early 16th century: the Accounts of the High Treasurer of Scotland for 1512 records that a royal servant, William Striveling, submitted his expenses (£11 4s and 8d; a considerable sum at that time) for assaying the lead mined on Islay, transportation and for building a house for a mine on Islay along with charcoal and other expenses made on tools etc from 23 August to 1 September 1511 (Caldwell 2008).

Throughout the 17th and 18th centuries lead mining occurred in fits and starts as leases for mineral rights changed hands between various eminent landowners, lairds and their tacksmen. The continued investment in lead mining on Islay probably stemmed from the fact that its lead ore was high in silver; an important by-product of lead mining that was extracted in this period by the method of cupellation (skimming the molten silver from the boiling ore). The Islay lead veins provided 40 ounces of silver from one ton of metal. The statistics of lead production on Islay between the years 1769 and 1774 are shown in Table 1.

Item

Tons

Cwt

Bar Lead

260

1

Ore

72

1

Slag of Lead

90

-

Table 1: Table showing lead output statistics between 1769 and 1774 after Wilson and Flett, Memoirs of the Geological Society 17, 65-73.

A major development was the establishment of the Islay Lead Mining Company Ltd in 1872, whose head office was in New Bond Street, London. This new consortium provided significant investment into what was then an ailing industry, including the construction of a new Cornish pumping engine house and ore-crushing plant at Mulreesh near Ballygrant.

A visitor's guide (Callender and Macaulay 1984) provides summary information on the location of the main mining areas on Islay but a much more extensive knowledge of the Islay leadmines was developed by an archaeological study conducted between 1991 and 1994 (Cressey 1993, 1994a-b, 1995) as part of a larger study to investigate the pollution history of mining on Islay. The areas known to have had a history of lead ore mining were explored by a combination of environmental sampling and archaeological recording. A series of deep cores were obtained from Lochs Lossit, Ballygrant, Finlaggan, Bharradail, all of which had a history of lead ore mining within their limestone catchment. Geochemical analysis of the loch sediment combined with 210Pb and 137Cs radiometric dating allowed annual sedimentation rates to be established (Appleby and Oldfield 1978 and 1984). The sites of former mines were explored and recorded archaeologically, principally by standing building survey and detailed topographical mapping. Select examples from the study are discussed briefly below.

Evidence for lead mining on Islay from the 1360s (Cressey 1995) was derived from a series of core samples taken from Loch Lossit in the vicinity of Knocklearoch (Glasco Beag lead workings) and from Loch Bharradail. This was a period when the Lords of The Isles had Finlaggan as their ceremonial centre (Caldwell 2008) and possibly indicates political control over the mineral wealth of the region.

The best preserved area of mining remains survived at Mulreesh (HER No. NR 46NW7; Figure 111 and Figure 113) where the remains of the mining structures built by the Islay Lead Mining Company are still extant, including the engine house, shafts, building remains, tailings and a rubble-built reservoir that provided water power to a trip hammer that crushed the ore prior to washing and grading. Contrastingly, the mine at South Ardachie, north of Loch Bharradail (HER No NR36 SE23), was less well preserved. Here the archaeological remains were mainly in the form of earthworks and a series of building platforms, bell-pits, trial pits and drainage adits.

The research strategy on Islay achieved a detailed historical pollution record as a result of lead mining in the study area. The archaeological surveys also provided new evidence on the nature and extent of the mine workings and pushed back the onset of mining to c.1360.

Future Research

The research strategy employed on Islay could be applied to the investigation of the metal mines of Argyll. Exploitation of metal ore within this maritime region has probably been carried out since the Prehistoric Period, but this has yet to be demonstrated. This would be an excellent research project for a postgraduate student with a background in industrial archaeology.